Fine amorphous metal wires

ABSTRACT

A fine amorphous metallic wire having a circular cross section and stability to a bias magnetic field, said wire being composed of an alloy having the following composition formula 
     
         (Co.sub.1-a-b Fe.sub.a M.sub.b).sub.100-x-y Si.sub.x B.sub.y 
    
     wherein M is at least one element selected from Cr, Mo, Ni, Nb, Ta, Pd, Pt, and Cu, x&lt;20 atomic %, 7 atomic %≦y&lt;35 atomic %, 7 atomic %&lt;x+y≦35 atomic %, 0.01≦a≦0.1, and 0.001≦b≦0.05. The fine amorphous metallic wire has low magnetostriction, high magnetic permeability, high saturation magnetic flux density, and excellent toughness, and is stable against a bias magnetic field. Hence, it can be used as a material for electromagnetic devices such as a coordinate reading device, a current sensor, an eddy current sensor, a magnetic sensor, or a displacement sensor.

FIELD OF THE INVENTION

This invention relates to fine amorphous metallic wires which arecircular in cross section and have stable properties against a biasmagnetic field while retaining the excellent properties of Co-typeamorphous alloys such as low magnetostriction, high magneticpermeability, and high saturation magnetic flux density.

BACKGROUND OF THE INVENTION

Amorphous magnetic alloy materials have been extensively studied forcommercialization because of their excellent electromagnetic properties.Particularly, Co-Fe-Si-B type amorphous alloys of specific compositionscan achieve very low magnetostriction, and are very much expected tofind applications as materials for magnetic heads, magnetic sensors,etc. Attempts have been actively made to improve their electromagneticproperties such as magnetic permeability and magnetic flux density byadding various elements to the Co-Fe-Si-B type amorphous alloys. Forexample, there are amorphous alloys in ribbon form having increasedmagnetic permeability as a result of adding suitable amounts of elementssuch as Nb, Ni, V, Ta, Ti, Zr, Cr, Mo, and W, as described, e.g., inJapanese Patent Application (OPI) Nos. 72715/79, 89918/79, 107826/79,107827/79, 13137/82, and 31053/83 (The term "OPI" as used herein refersto a "published unexamined Japanese patent application.").

Japanese Patent Application (OPI) No. 79052/82 (corresponding to U.S.Pat. No. 4,527,614 and European Patent 50,479) discloses high-qualityCo-type fine amorphous metallic wires circular in cross section whichhave a very uniform shape with a circularity of at least 90% and adiameter variation of not more than 4%.

Amorphous metallic ribbons produced by the one roll method by thepresent inventors from conventional Co-type amorphous metals, forexample, an alloy having the composition (Co₀.92 Fe₀.06 Cr₀.02)₇₅ Si₁₀B₁₅ or an alloy having the composition (Co₀.92 Fe₀.06 Ta₀.02)₇₅ Si₁₀ B₁₅described in Japanese Patent Application (OPI) No. 107827/79, an alloyhaving the composition (Co₀.91 Fe₀.06 -Nb₀.03)₇₇ Si₁₅ B₈ described inJapanese Patent Application (OPI) No. 31053/83, and an alloy having thecomposition (Co₀.92 Fe₀.06 Ni₀.02)₇₈ Si₁₃ B₉ or an alloy having thecomposition (Co₀.91 Fe₀.06 Mo₀.03)₇₈ Si₁₃ B₉ described in JapanesePatent Application (OPI) No. 13137/82 had low magnetostriction, highmagnetic permeability, and high saturation magnetic flux density, butwhen a bias magnetic field was applied thereto, the magneticpermeability decreased abruptly. Specifically, when amorphous metallicribbons having a thickness of about from 5 to 100 microns (μm) and awidth of from 2 to 100 mm were produced by jetting a molten mass of aCo-Fe-Cr-Si-B type alloy, a Co-Fe-Mo-Si-B type alloy, or a Co-Fe-Ni-Si-Btype alloy onto a rotating cooling roll made of a material having highthermal conductivity such as a copper, these ribbons markedly decreasedin magnetic permeability under the influence of a bias magnetic field.

Such ribbon which decreases in magnetic permeability in a bias magneticfield cannot be used in practical applications because when it isapplied, for example, to a coordinates reading device, signals obtainedbecome abruptly weak due to even a slight bias magnetic field, forexample by the influence of the earth's magnetism owing to thedifferences in the directions of east, west, south, and north, or by theinfluence of a magnetized body near the measuring instrument.

The Co-type fine amorphous metallic wires described in Japanese PatentApplication (OPI) No. 79052/82 have superior electromagnetic propertiesand corrosion resistance, but their magnetic permeability decreasesunder the influence of a bias magnetic field. Hence, they are not fullyacceptable as a material for a coordinates reading device, for example.

SUMMARY OF THE INVENTION

One object of this invention is to provide an amorphous electromagneticalloy material which is substantially invulnerable to influences of abias magnetic field while retaining the low magnetostriction, highmagnetic permeability, and high saturation magnetic flux densitycharacteristics of Co-type amorphous alloy.

The present inventors have made extensive investigations in order toachieve this object, and have found that fine amorphous metallic wireshaving substantial invulnerability to a bias magnetic field and anincreased permeability without a decrease in saturation magnetic fluxdensity can be obtained by adding a specific amount of at least one ofCr, Mo, Ni, Nb, Ta, Pd, Pt, and Cu to an alloy of Co, Fe, Si, and B inspecific proportions, and processing the resulting alloy such that theresulting wires have a circular cross section.

According to this invention, there is provided a fine amorphous metallicwire having a circular cross section and stability to a bias magneticfield, said wire being composed of an alloy having the compositionformula

    (Co.sub.1-a-b Fe.sub.a M.sub.b).sub.100-x-y Si.sub.x B.sub.y

wherein M is at least one element selected from Cr, Mo, Ni, Nb, Ta, Pd,Pt, and Cu, and x<20 atomic%, 7 atomic%≦y<35 atomic%, 7 atomic%<x+y≦35atomic%, 0.01 atomic%≦a≦0.1 atomic%, and 0.001≦b≦0.05.

The fine amorphous metallic wire has low magnetostriction, high magneticpermeability, high saturation magnetic flux density, and excellenttoughness, and is stable to a bias magnetic field. Hence, it is veryuseful as a material for electromagnetic devices such as coordinatesreading devices, current sensors, eddy current sensors, magneticsensors, displacement sensors, etc., to which the application ofconventional Co-type amorphous alloys is difficult.

The fine amorphous metallic wire of this invention also has excellentcorrosion resistance and fatigue characteristics, and does not involveany trouble during use in a corrosive atmosphere or at sites which aresubject to strains.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The fine amorphous metallic wire of this invntion is a material havinglow magnetostriction, high magnetic permeability, high saturationmagnetic flux density, substantial invulnerability to influences of abias magnetic field, and excellent toughness. To obtain theseproperties, the composition of the alloy should be limited as describedbelow.

The total sum of Si and B should exceed 7 atomic% but not be more than35 atomic%, and preferably is at least 15 atomic% but not more than 32atomic%. If the total of Si and B is 7 atomic% or less, or more than 35atomic%, an amorphous single phase fine metallic wire cannot beobtained, and the resulting fine metallic wire has poor toughness, whichcreates serious problems in after-processing. This is not industriallydesirable.

Within the above specified total amount of Si and B, the proportion ofSi should be less than 20 atomic%, and preferably is at least 7.5atomic% but not more than 17.5 atomic%. If the proportion of Si is 20atomic% or above, an amorphous single phase fine metallic wire cannot beobtained, and the resulting metallic wire has poor toughness.

Likewise, the proportion of B should be at least 7 atomic% but less than35 atomic%, and preferably is at least 7.5 atomic% but not more than 25atomic%. If the proportion of B is less than 7 atomic% or at least 35atomic%, the resulting metallic wire has poor toughness.

Taking the total of Co, Fe, and M as 1, the proportion of Fe should beat least 0.01 but not more than 0.1. If the proportion of Fe exceeds0.1, the magnetostriction increases on the positive side. If theproportion of Fe is less than 0.01, the magnetostriction increases onthe negative side.

M is at least one element selected from Cr, Mo, Ni, Nb, Ta, Pd, Pt, andCu. Its proportion should be at least 0.001 but not more than 0.05, andpreferably is at least 0.003 but not more than 0.04. If it exceeds 0.05,the magnetic permeability of the fine wire decreases very much and thewire is not practical. If it is less than 0.001, no effect due to theadding of the element M is observed, and the magnetic permeability isgreatly decreased by the influence of a bias magnetic field. The finemetallic wire of this invention may contain impurities in amountspresent in ordinary industrial materials.

To produce the fine wire of this invention, the above alloy can bemelted and quenched and solidified by a spinning method in a rotatingliquid which is particularly preferably used in this invention. Thespinning method in a rotating liquid is described, for example, inJapanese patent Application (OPI) No. 165016/81 (corresponding to U.S.Pat. No. 4,523,626 and European Pat. No. 39,169) and Japanese patentapplication (OPI) No. 79052/82 (corresponding to U.S. Pat. No. 4,527,614and European Pat. No. 50,479). Specifically, water is put into arotating drum, and a water film is formed on the inner wall of the drumby centrifugal force. The molten alloy is jetted into the water filmfrom a spinning nozzle having an orifice diameter of from about 80 to200 microns (μm) to form a fine wire having a circular cross section. Toobtain a uniform continuous fine wire, it is desirable to make theperipheral speed of the rotating drum equal to, or higher than, thespeed of the molten metal flow jetted from the spinning nozzle, andparticularly preferbly higher than the speed of the molten metal flow byfrom 5 to 30%. Preferably, the angle formed between the molten metalflow jetted from the spinning nozzle and the water film formed on theinner wall of the drum is at least 20°. Further, the fine wire of thisinvention can be produced by the other methods, for example, Kaneshmethod as described in U.S. Pat. No. 3,845,805.

The fine amorphous metallic wire of this invention generally has adiameter of about from 50 to 250 micrometers and a circularity of atleast 60% (method of determination described below), preferably at least80%, especially preferred at least 90%, and preferably has a uniformshape shown by a diameter variation of not more than 4%.

The fine wire of this invention has low magnetostriction, high magneticpermeability, high saturation magnetic flux density, and excellenttoughness, and hardly decreases in magnetic permeability when subjectedto a bias magnetic field. For example, a fine amorphous metallic wirecomposed of (Co₀.91 Fe₀.06 -Mo₀.03)₇₂.5 Si₁₂.5 B₁₅ having a circularcross section and high quality can be bent by 180° bending property andhas excellent toughness, a magnetic flux density (B₂₀) under theapplication of a magnetic field of 20 Oe of 7.3 KG, a magneticpermeability (μ₁₀₀) at a frequency of 100 KHz of as high as 1805, and amagnetostriction of nearly zero. Its Hc is 0.064 Oe, which is higherthan the Hc (0.036 Oe) of a conventional fine amorphous metallic wirecomposed of (Co₀.94 Fe₀.06)₇₂.5 Si₁₂.5 B₁₅. Thus, this fine amorphousmetallic wire is substantially invulnerable to the influences by a biasmagnetic field, and is magnetically stable. However, an amorphous ribbonhaving the composition (Co₀.91 Fe₀.06 Mo₀.03)₇₂.5 Si₁₂.5 B₁₅ hasapproximately the same toughness and B₂₀ value as the fine amorphousmetallic wire of this invention having the same composition, but has aμ₁₀₀ of as low as 800 and an Hc value of as low as 0.007 Oe, andtherefore is influenced by even a slight bias magnetic field such as theearth's magnetism and decreases greatly in magnetic permeability. Forexample, when such ribbon is used in a coordinates reading device or thelike, signals obtained may sometimes become very small, and itsstability to a bias magnetic field is extremely low.

High-quality fine amorphous magnetic metallic wires having thecomposition (Co₀.93 Fe₀.065 Nb₀.005)₇₂.5 -Si₁₂.5 B₁₅ and a circularcross section can be bent by 180° bending property and have excellenttoughness. They have a magnetic flux density (B₂₀), under theapplication of a magnetic field of 20 Oe, of 7.5 KG, a magneticpermeability (μ₁₀₀) at a frequency of 100 KHz of as high as 1940, and amagnetostriction of nearly zero. They are substantially invulnerable toinfluences of a bias magnetic field, and are magnetically stable.However, an amorphous ribbon having the same composition (Co₀.93-Fe₀.065 Nb₀.005)₇₂.5 Si₁₂.5 B₁₅ has similar toughness and B₂₀ to thefine amorphous metallic wires of this invention having the samecomposition, but has a μ₁₀₀ of as low as 950 and an Hc of as low as0.003 Oe. Hence, it undergoes effects of a slight bias magnetic fieldsuch as the earth's magnetism and greatly decreases in magneticpermeability. When such ribbon is used, for example, in a coordinatereading device, the signals obtained may become very small, and itsstability to a bias magnetic field is very low.

The fine amorphous metallic wire of this invention is stable against abias magnetic field, and particularly has a V_(H) value, definedhereinbelow, of not more than 1.5, preferably not more than 1.2, morepreferably not more than 0.75, showing better stability thanconventional ribbon having a V_(H) of from 2.1 to 2.6.

The following examples illustrate the present invention morespecifically. However, the invention is not limited to these examples.

EXAMPLES 1 TO 25 AND COMPARATIVE EXAMPLES 1 TO 35

In each run, each of Co type alloys and Co-Fe-Si-B-M type alloys havingthe compositions shown in Table 1 was melted in an argon gas atmosphere,and jetted from a quartz glass spinning nozzle having an orificediameter of 0.13 mm under an argon gas jetting pressure of 4.5 kg/cm²into a cooling liquid, 25 mm deep, kept at a temperature of 4° C. andformed within a cylindrical drum having an inside diameter of 500 mm androtating at a speed of 300 rpm to quench and coagulate the molten alloyand to produce a continuous fine amorphous metallic wire having acircular cross section and a diameter of 120 microns (μm).

At this time, the distance between the spinning nozzle and the surfaceof the rotating cooling liquid was maintained at 3 mm, and the angleformed between the molten metal stream jetted out from the spinningnozzle and the surface of the rotating cooling liquid was about 65°.

For comparison, an amorphous alloy ribbon having the composition shownin Table 1 and a flat cross section was produced by jetting out themolten alloy onto a rotating cooling roll composed of copper(Comparative Examples 3, 4, 7, 10, 15, 16, 23, 24, 29, and 30).

The electromagnetic properties, 180° bending property, and shape of theresulting amorphous alloy wire or ribbon were measured, and the resultsare summarized in Table 1.

The circularity was determined by selecting 10 points in the lengthwisedirection of the continuous fine wire, and calculating an average of theratios (r/R×100(%)) of the long diameters (R) and the short diameters(r) of the cross sections of these points.

The diameter variation was determined by a coefficient of variation ofthe average wire diameter obtained by causing the fine wire to run 50 mby a laser wire diameter measuring instrument (SLG-104 type, made byShin Nippon Kagaku Seisakusho Co., Ltd.) and measuring the continuousaverage wire diameter. That is, its diameter variation means acoefficient of variation of a long diameter in the lengthwise directionwhich is represented by the formula (σ_(n) /n×100(%)), wherein x is anaverage of the diameters measured at each points in the lengthwisedirection of the wire when caused the wire to run 50 m, and σ_(n) is astandard deviation of the measured values at each portion.

The coercivity Hc at a.c. 50 Hz and the magnetic flux density B₂₀ at 20Oe were measured from an a.c. magnetization curve determined by a BHcurve tracer made by Riken Electronics Co., Ltd.

The magnetic permeability μ(10 mOe, 100 KHz) was measured by animpedance analyzer (4192 ALF, made by YHP) on a fine wire or ribbonsample having a length of 40 cm inserted into a coil.

The magnetostriction was measured by using a magnetostriction measuringdevice made by Naruse Scientific Machine Co., Ltd.

The stability to a bias magnetic field, indicated by the V_(H) value inTable 1 below, was determined as follows: by using an impedanceanalyzer, the magnetic permeability μ(100 KHz) of a sample was measuredwhile the bias magnetic field was continuously varied from 0 Oe to 0.4Oe in the axial direction of the sample. From the bias magneticfield-permeability curve, the variation V_(H) of the magneticpermeability with respect to the bias magnetic field was calculated inaccordance with the equation ##EQU1## wherein (μ₁₀₀)₀ is the magneticpermeability in the absence of the bias magnetic field and (μ₁₀₀)₀.4 isthe magnetic permeability under the application of a bias magnetic fieldof 0.4 e,uml/O/ e.

                                      TABLE 1                                     __________________________________________________________________________                                            180°                                                                        Shape                                                            Hc      Bending                                                                            Circularity                                                                         Diameter                   Example No.                                                                          Alloy Composition (atomic %)                                                                       μ.sub.100                                                                      (Oe)                                                                              V.sub.H                                                                           Property                                                                           (%)   Variation                  __________________________________________________________________________                                                       (%)                        Comp. Ex.  1                                                                         (Co.sub.0.94 Fe.sub.0.06).sub.72.5 Si.sub.12.5 B.sub.15                                            1820                                                                              0.036                                                                             2.01                                                                              possible                                                                           96    1.3                        Comp. Ex.  2                                                                         (Co.sub.0.9365 Fe.sub.0.063 Mo.sub.0.0005).sub.72.5 Si.sub.12.5               B.sub.15             1810                                                                              0.037                                                                             1.94                                                                              "    96    1.2                        Ex.  1 (Co.sub.0.93 Fe.sub.0.065 Mo.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1815                                                                              0.058                                                                             0.24                                                                              "    97    1.0                        Comp. Ex.  3                                                                         (Co.sub.0.93 Fe.sub.0.065 Mo.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15              800                                                                              0.003                                                                             2.57                                                                              "     1    --                         Ex.  2 (Co.sub.0.91 Fe.sub.0.06 Mo.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1805                                                                              0.073                                                                             0.30                                                                              "    97    1.3                        Comp. Ex.  4                                                                         (Co.sub.0.91 Fe.sub.0.06 Mo.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15              800                                                                              0.007                                                                             2.64                                                                              "     1    --                         Comp. Ex.  5                                                                         (Co.sub.0.875 Fe.sub.0.055 Mo.sub.0.07).sub.72.5 Si.sub.12.5                  B.sub.15              925                                                                              0.096                                                                             0.23                                                                              breaks                                                                             96    1.2                        Comp. Ex.  6                                                                         (Co.sub.0.9365 Fe.sub.0.063 Ni.sub.0.0005).sub.72.5 Si.sub.12.5               B.sub.15             1760                                                                              0.038                                                                             1.90                                                                              possible                                                                           96    1.2                        Ex.  3 (Co.sub.0.928 Fe.sub.0.067 Ni.sub.0.005).sub.72.5 Si.sub.12.5                 B.sub.15             1730                                                                              0.065                                                                             0.29                                                                              "    96    1.1                        Ex.  4 (Co.sub.0.894 Fe.sub.0.076 Ni.sub.0.03).sub.72.5 Si.sub.12.5                  B.sub.15             1715                                                                              0.071                                                                             0.28                                                                              "    96    1.2                        Comp. Ex.  7                                                                         (Co.sub.0.894 Fe.sub.0.076 Ni.sub.0.03).sub.72.5 Si.sub.12.5                  B.sub.15              750                                                                              0.005                                                                             2.16                                                                              "     1    --                         Comp. Ex.  8                                                                         (Co.sub.0.843 Fe.sub.0.087 Ni.sub.0.07).sub.72.5 Si.sub.12.5                  B.sub.15              905                                                                              0.098                                                                             0.28                                                                              "    95    1.2                        Comp. Ex.  9                                                                         (Co.sub.0.9365 Fe.sub.0.063 Cr.sub.0.0005).sub.72.5 Si.sub.12.5               B.sub.15             1790                                                                              0.037                                                                             1.96                                                                              "    96    1.1                        Ex.  5 (Co.sub.0.93 Fe.sub.0.065 Cr.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1775                                                                              0.062                                                                             0.38                                                                              "    96    1.2                        Ex.  6 (Co.sub.0.91 Fe.sub.0.06 Cr.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1720                                                                              0.070                                                                             0.36                                                                              "    97    1.0                        Comp. Ex. 10                                                                         (Co.sub.0.91 Fe.sub.0.06 Cr.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15              780                                                                              0.004                                                                             2.37                                                                              "     1    --                         Comp. Ex. 11                                                                         (Co.sub.0.875 Fe.sub.0.055 Cr.sub.0.07).sub.72.5 Si.sub.12.5                  B.sub.15              840                                                                              0.096                                                                             0.35                                                                              "    96    1.2                        Comp. Ex. 12                                                                         (Co.sub.0.93 Fe.sub.0.065 Cr.sub.0.005).sub.90 Si.sub.5 B.sub.5                                    --  --  --  breaks                                                                             94    1.4                        Comp. Ex. 13                                                                         (Co.sub.0.93 Fe.sub.0.065 Cr.sub.0.05).sub.72 Si.sub.23 B.sub.5                                    --  --  --  "    95    1.4                        Ex.  7 (Co.sub.0.907 Fe.sub.0.063 Cr.sub.0.01 Mo.sub.0.02).sub.72.5                  Si.sub.12.5 B.sub.15 1785                                                                              0.058                                                                             0.32                                                                              possible                                                                           96    1.2                        Ex.  8 (Co.sub.0.93 Fe.sub.0.065 Ni.sub.0.002 Cr.sub.0.003).sub.72.5                 Si.sub.12.5 B.sub.15 1750                                                                              0.063                                                                             0.31                                                                              "    97    1.2                        Ex.  9 (Co.sub.0.93 Fe.sub.0.065 Ni.sub.0.002 Mo.sub.0.003).sub.72.5                 Si.sub.12.5 B.sub.15 1765                                                                              0.061                                                                             0.29                                                                              "    97    1.1                        Comp. Ex. 14                                                                         (Co.sub.0.9365 Fe.sub.0.063 Nb.sub.0.0005).sub.72.5 Si.sub.12.5               B.sub.15             1815                                                                              0.037                                                                             1.96                                                                              "    97    1.1                        Ex. 10 (Co.sub.0.93 Fe.sub.0.065 Nb.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1940                                                                              0.060                                                                             0.22                                                                              "    97    1.2                        Comp. Ex. 15                                                                         (Co.sub.0.93 Fe.sub.0.065 Nb.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub. 15             950                                                                              0.003                                                                             2.56                                                                              "     1    --                         Ex. 11 (Co.sub.0.91 Fe.sub.0.06 Nb.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1870                                                                              0.069                                                                             0.24                                                                              "    98    1.1                        Comp. Ex. 16                                                                         (Co.sub.0.91 Fe.sub.0.06 Nb.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15              700                                                                              0.004                                                                             2.43                                                                              "     1    --                         Comp. Ex. 17                                                                         (Co.sub.0.875 Fe.sub.0.055 Nb.sub.0.07).sub.72.5 Si.sub.12.5                  B.sub.15              900                                                                              0.094                                                                             0.25                                                                              breaks                                                                             95    1.3                        Ex. 12 (Co.sub.0.93 Fe.sub.0.065 Nb.sub.0.005).sub.74.5 Si.sub.16.5                  B.sub.9              1820                                                                              0.057                                                                             0.25                                                                              possible                                                                           96    1.1                        Ex. 13 (Co.sub.0.93 Fe.sub.0.065 Nb.sub.0.005).sub.75 Si.sub.7.5 B.sub.17                                 1825                                                                              0.056                                                                             0.27                                                                              "    97    1.0                        Comp. Ex. 18                                                                         (Co.sub.0.93 Fe.sub.0.065 Nb.sub.0.005).sub.90 Si.sub.5 B.sub.5                                    --  --  --  breaks                                                                             95    1.2                        Comp. Ex. 19                                                                         (Co.sub.0.93 Fe.sub.0.065 Nb.sub.0.005).sub.72 Si.sub.23 B.sub.5                                   --  --  --  "    92    1.4                        Comp. Ex. 20                                                                         (Co.sub.0.9365 Fe.sub.0.063 Ta.sub.0.0005).sub.72.5 Si.sub.12.5               B.sub.15             1810                                                                              0.038                                                                             1.93                                                                              possible                                                                           96    1.2                        Ex. 14 (Co.sub.0.93 Fe.sub.0.065 Ta.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1800                                                                              0.051                                                                             0.42                                                                              "    97    1.0                        Ex. 15 (Co.sub.0.91 Fe.sub.0.06 Ta.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1790                                                                              0.054                                                                             0.36                                                                              "    97    1.0                        Comp. Ex. 21                                                                         (Co.sub.0.878 Fe.sub.0.052 Ta.sub.0.07).sub.72.5 Si.sub.12.5                  B.sub.15              890                                                                              0.085                                                                             0.29                                                                              breaks                                                                             96    1.0                        Comp. Ex. 22                                                                         (Co.sub.0.9365 Fe.sub.0.063 Pd.sub.0.0005).sub.72.5 Si.sub.12.5               B.sub.15             1810                                                                              0.037                                                                             1.95                                                                              possible                                                                           95    1.4                        Ex. 16 (Co.sub.0.935 Fe.sub.0.06 Pd.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1790                                                                              0.052                                                                             0.60                                                                              "    95    1.3                        Comp. Ex. 23                                                                         (Co.sub.0.935 Fe.sub.0.06 Pd.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15              735                                                                              0.007                                                                             2.37                                                                              "     1    --                         Ex. 17 (Co.sub.0.91 Fe.sub.0.06 Pd.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1750                                                                              0.068                                                                             0.52                                                                              "    96    1.3                        Comp. Ex. 24                                                                         (Co.sub.0.91 Fe.sub.0.06 Pd.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15              690                                                                              0.009                                                                             2.29                                                                              "     1    --                         Comp. Ex. 25                                                                         (Co.sub.0.87 Fe.sub.0.06 Pd.sub.0.07).sub.72.5 Si.sub.12.5                    B.sub.15              850                                                                              0.084                                                                             0.48                                                                              breaks                                                                             95    1.3                        Comp. Ex. 26                                                                         (Co.sub.0.9395 Fe.sub.0.06 Pt.sub.0.0005).sub.72.5 Si.sub.12.5                B.sub.15             1800                                                                              0.038                                                                             1.91                                                                              possible                                                                           96    1.1                        Ex. 18 (Co.sub.0.935 Fe.sub.0.06 Pt.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1760                                                                              0.056                                                                             0.30                                                                              "    96    1.0                        Ex. 19 (Co.sub.0.91 Fe.sub.0.06 Pt.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1720                                                                              0.064                                                                             0.28                                                                              "    97    1.0                        Comp. Ex. 27                                                                         (Co.sub.0.87 Fe.sub.0.06 Pt.sub.0.07).sub.72.5 Si.sub.12.5                    B.sub.15              840                                                                              0.095                                                                             0.25                                                                              breaks                                                                             95    1.3                        Comp. Ex. 28                                                                         (Co.sub.0.9395 Fe.sub.0.06 Cu.sub.0.0005).sub.72.5 Si.sub.12.5                B.sub.15             1790                                                                              0.039                                                                             1.88                                                                              possible                                                                           95    1.4                        Ex. 20 (Co.sub.0.935 Fe.sub.0.06 Cu.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15             1700                                                                              0.061                                                                             0.35                                                                              "    96    1.1                        Comp. Ex. 29                                                                         (Co.sub.0.935 Fe.sub.0.06 Cu.sub.0.005).sub.72.5 Si.sub.12.5                  B.sub.15              700                                                                              0.008                                                                             2.28                                                                              "     1    --                         Ex. 21 (Co.sub.0.91 Fe.sub.0.06 Cu.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15             1690                                                                              0.072                                                                             0.31                                                                              "    96    1.0                        Comp. Ex. 30                                                                         (Co.sub.0.91 Fe.sub.0.06 Cu.sub.0.03).sub.72.5 Si.sub.12.5                    B.sub.15              650                                                                              0.013                                                                             2.20                                                                              "     1    --                         Comp. Ex. 31                                                                         (Co.sub.0.87 Fe.sub.0.06 Cu.sub.0.07).sub.72.5 Si.sub.12.5                    B.sub.15              870                                                                              0.084                                                                             0.29                                                                              breaks                                                                             94    1.6                        Comp. Ex. 32                                                                         (Co.sub.0.9344 Fe.sub.0.065 Nb.sub.0.0003 Ta.sub.0.0003).sub.72.5             Si.sub.12.5 B.sub.15 1790                                                                              0.038                                                                             1.93                                                                              possible                                                                           95    1.3                        Ex. 22 (Co.sub.0.925 Fe.sub.0.065 Nb.sub.0.005 Ta.sub.0.005).sub.72.5                Si.sub.12.5 B.sub.15 1780                                                                              0.062                                                                             0.23                                                                              "    96    1.1                        Ex. 23 (Co.sub.0.905 Fe.sub.0.065 Nb.sub.0.02 Ta.sub.0.01).sub.72.5                  Si.sub.12.5 B.sub.15 1805                                                                              0.065                                                                             0.21                                                                              "    97    1.0                        Comp. Ex. 33                                                                         (Co.sub.0.855 Fe.sub.0.065 Nb.sub.0.05 Ta.sub.0.03).sub.72.5                  Si.sub.12.5 B.sub.15  800                                                                              0.090                                                                             0.20                                                                              breaks                                                                             96    1.0                        Comp. Ex. 34                                                                         (Co.sub.0.9394 Fe.sub.0.06 Pd.sub.0.0003 Cu.sub.0.0003).sub.72.5              Si.sub.12.5 B.sub.15 1770                                                                              0.039                                                                             1.90                                                                              possible                                                                           94    1.3                        Ex. 24 (Co.sub.0.93 Fe.sub.0.06 Pd.sub.0.005 Cu.sub.0.005).sub.72.5                  Si.sub.12.5 B.sub.15 1660                                                                              0.059                                                                             0.38                                                                              "    95    1.3                        Ex. 25 (Co.sub.0.91 Fe.sub.0.06 Pd.sub.0.02 Cu.sub.0.01).sub.72.5                    Si.sub.12.5 B.sub.15 1600                                                                              0.067                                                                             0.56                                                                              "    95    1.2                        Comp. Ex. 35                                                                         (Co.sub.0.86 Fe.sub.0.06 Pd.sub.0.03 Cu.sub.0.05).sub.72.5                    Si.sub.12.5 B.sub.15 --  --  --  breaks                                                                             93    1.7                        __________________________________________________________________________

It is clearly seen from Table 1 that in Examples 1, 2, 4, 6, 10, 11, 16,17, 20, and 21, the V_(H) values are much smaller than those inComparative Examples 3, 4, 7, 10, 15, 16, 23, 24, 29, and 30,respectively. In other words, amorphous metallic ribbons have largerV_(H) values than fine amorphous metallic wires of the same alloycomposition, and stability to a bias magnetic field is inherent in thefine amorphous metallic wires of this invention having a circular crosssection.

In Examples 1 to 25, the V_(H) values are from 0.2 to 0.6 which are muchsmaller than the V_(H) value of 2.01 in Comparative Example 1 in whichno M element was added, and the stability to a bias magnetic field isvery great. For example, the decreases of magnetic permeability inComparative Example 1, Example 2, and Comparative Example 4 underinfluence of a bias magnetic field were as follows. In ComparativeExample 1, μ₁₀₀ was 1820 in the absence of a bias magnetic field, butdecreased to 286 when a bias magnetic field of 0.4 Oe was applied. InComparative Example 3, μ₁₀₀ was 800 in the absence of a bias magneticfield, but decreased to 70 when a bias magnetic field of 0.4 Oe wasapplied. In contrast, in Example 2, μ₁₀₀ was 1805 in the absence of abias magnetic field, and 1370 even when a bias magnetic field of 0.4 Oewas applied; furthermore, the decrease of magnetic permeability was verysmall.

Since Comparative Examples 8, 11, 14, 20, 22, 26, 28, 32, and 34 hadcompositions outside the present invention, the decrease of magneticpermeability under a bias magnetic field was large, and the V_(H) valueswere accordingly large. In Comparative Examples 5, 12, 13, 17-19, 21,25, 27, 31, 33, and 35, the compositions were outside the scope of theinvention. Hence, the products had poor toughness and could not be bentby 180° bending property. In particular, the alloys in ComparativeExamples 12, 13, 18, 19, and 35 did not become amorphous, butcrystallized. They were brittle and did not show soft magnetism.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A fine magnetic amorphous metal wire having acircular cross section and stability to a bias magnetic field, said wirebeing composed of an alloy having the composition formula

    (Co.sub.1-a-b Fe.sub.a M.sub.b).sub.100-x-y Si.sub.x B.sub.y

wherein M is at least one element selected from Cr, Mo, Ni, Nb, Ta, Pd,Pt, and Cu, x<20 atomic%, 7 atomic%≦y<35 atomic%, 7 atomic%<x+y≦35atomic%, 0.01≦a≦0.1, and 0.001≦b≦0.05.
 2. A fine magnetic amorphousmetal wire as in claim 1, wherein b is at least 0.003 but not more than0.04.
 3. A fine magnetic amorphous metal wire as in claim 1, wherein x+yis at least 15 atomic% but not more than 32 atomic%.
 4. A fine magneticamorphous metal wire as in claim 1, wherein y is at least 7.5 atomic %but not more than 25 atomic%.
 5. A fine magnetic amorphous metal wire asin claim 1, wherein the wire has a circularity of at least 60%.
 6. Afine magnetic amorphous metal wire as in claim 1, wherein the wire has acircularity of at least 80%.
 7. A fine magnetic amorphous metal wire asin claim 1, wherein the wire has a circularity of at least 90%.
 8. Afine magnetic amorphous metal wire as in claim 1, wherein said wire hasa V_(H) value of not more than 1.5.
 9. A fine magnetic amorphous metalwire as in claim 1, wherein said wire has a V_(H) value of not more than1.2.
 10. A fine magnetic amorphous metal wire as in claim 1, whereinsaid wire has a V_(H) value of not more than 0.75.